Radiation Hazards and the Cancer Risk Assessments in the Sediments of Timsah Lake, Egypt

Abstract

Timsah Lake is one of the most fish productive lakes in Egypt. It is located at the midpoint of Suez Canal with surface area of about 16 km2. The lake receives about 833,000 m3daily of wastewater and sewage wastes from agriculture, industry and domestic drains. The activity concentrations of the natural radionuclides; 238U, 232Th and 40K were measured using gamma-ray spectrophotometer at 24 stations covering the whole area of the lake and the Western Bay. The average activities of 238U, 232Th and 40K were; 21.66 ± 11.20, 21.42 ± 11.68 and 200.30 ± 141.10 Bq/kg respectively. The averages of radiation hazard parameters; the absorbed and effective dose rate (D), the annual effective dose equivalent (AEDE), radium equivalent (Raeq), the external hazard index (Hex) and the representative level index (Iγr) were; 30.85 nGy h-1, 37.84 μSv/y, 67.02 Bq/kg, 0.18 (lower than the unity) and 0.23 respectively. The distribution patterns showed significant high variations in the radionuclides activities and the hazard parameters between the investigated stations. The Western Bay stations and the path zone interlinked between the bay and the lake showed the high radionuclide activities and high radiation hazards indicating to the sewage wastes and wastewater runoff are the essential sources of the high natural radionuclide activities and radiation hazards. The average of the excess lifetime cancer risk (ELCR) was 132.43 × 10-6significantly lower than the worldwide average. The highest recorded level of ELCR was reached 308.38 × 10-6observed in the interlink zone between the bay and the lake away from fishing stations and recreational zones. Statistical analyses indicated that the radionuclides 238U and 232Th are the sources of the elevated radiation hazards with nearly equal intensities. © 2020. All Rights Reserved.